1. Field of the Invention
This invention relates to an image recording apparatus for representing half-tones of an image, and more particularly to a half-tone recording apparatus of the beam scanning type in which a beam of light, electron or the like is modulated and deflected by recording information and scans a recording medium to thereby record information on the recording medium, and in which at least the expanse of the recording beam is increased or decreased in accordance with the density information of the image and if required, the intensity of the beam is also varied, to thereby enable half-tones of the image to be represented.
2. Description of the Prior Art
In the art of photography using a recording material such as silver salt or the like to represent the tones of an image, continuous tone representation is possible, whereas depending on the type of the recording material, the exposure vs. density characteristic curve, which is representative of the variation in density for the variation in exposure, has a narrow linear range and the use of such a recording material results in a disadvantage that the resultant image representation lacks half-tones of the image, thus being inferior in quality, because the density of the material cannot linearly follow the variation in density of the image. In order to overcome this, recording may be effected with the exposure simply increased or decreased but this is not sufficient to represent the delicate half-tones of the image.
Recording materials used in the electronic or the electrostatic photography may be mentioned as such recording material. Copying machines using such recording materials are commercially available but, when half-tones are to be represented by these machines, it is well-known that the use of an image original in the form of screen dots is the most effective. This is not restricted to copying machines, but in the ordinary field of printing, half-tone representation is accomplished by using the screen dot system when photographs or the like having continuous tones are to be printed.